About the Authors

Hilary R. Davies

h.davies.12@ucl.ac.uk

Affiliation University College London Department of Primary Care and Population Health, Rowland Hill Street, London, NW3 2PF, United Kingdom

Irwin Nazareth

Affiliation University College London Department of Primary Care and Population Health, Rowland Hill Street, London, NW3 2PF, United Kingdom

Irene Petersen

Affiliation University College London Department of Primary Care and Population Health, Rowland Hill Street, London, NW3 2PF, United Kingdom

Competing Interests

Irene Peterson is a PLOS ONE Editorial Board member. This does not alter the authors' adherence to PLOS ONE Editorial policies and criteria.

Author Contributions

Conceived and designed the experiments: HD IP IN. Analyzed the data: HD. Wrote the paper: HD IP IN.